I chanced upon this bit of ancient ‘wisdom’ in a random fantasy novel and immediately discarded it as just a saying. But it would soon unlock an immense appreciation for a simple and powerful tool – observation. Luckily it was the rainy season, and a few days later, a friend mentioned that the sky had a stronger red tinge than before. I remembered the saying and quoted it as a joke. It soon turned into a wager, and to my surprise, the next day was indeed a bright and clear one. Having won the bet, I once again discarded it as a chance event, but I kept observing, and it soon seemed that there was a pattern. I set out to get to the bottom of it, and as it turns out, it is backed by pretty hefty yet simple science.

We know that wind blows from areas of high-pressure to low-pressure areas. Therefore, wind, along with all the moisture, moves to low-pressure regions, which leads to windy and humid weather, conducive to the rain-like conditions. When all the rain-bearing clouds have moved away, the high-pressure area is left with dry and pleasant conditions.

These high-pressure systems are capable of trapping dust and small particulate matter in the sky. These particles cause scattering of light, blocking blue light while letting red light pass. This gives a red tinge to the sky.

Interestingly, the prevailing wind system in the temperate latitudes is the Westerlies, which blow from West to East. They are caused by the rotation of the Earth and are responsible for the movement of low and high-pressure systems across countries and continents.

At sunset, the light comes from the West, while at sunrise, the light comes from the East. Therefore, a red sky at night implies a high-pressure system to the West that will reach you the next day, leading to a sunny and pleasant day. On the other hand, a red sky in the morning means that the high-pressure system has already passed you, and hence there is a good chance of precipitation.

If it is an East to West wind system, like in the tropics, precisely the opposite would be true.

Some versions of the saying have been around since before the Medieval era, and have no doubt come to the aid of countless sailors, shepherds, and soldiers. All because of a simple observation. An observation that was once the bedrock of science has been shunned to the sidelines. Knowledge has increased, but the intrinsic beauty of gaining knowledge, observing the world around us, and curious pondering has been discarded.

It is said that if you observe a grain of sand closely enough you can understand the whole world. Although an exaggerated statement, it does get it right – simple observations, layered on top of another and explored, is the essence of science.

Science is not research and entrepreneurship and awards. Science need not even be about solving problems and challenges for society. Science is about the art of discovery, about knowledge for knowledge’s sake, and about the euphoria of knowing.

- Rohan Dandavate